The invention relates to a burner for use in the partial combustion of carbonaceous fuels, and particularly for the partial combustion of finely divided solid fuel such as pulverized coal, in which the fuel is introduced together with an oxygen-containing gas into a reactor space operating under elevated pressure up to 100 bar for producing pressurized synthesis gas, fuel gas or reducing gas.
Partial combustion, also known as gasification, of a solid carbonaceous fuel is obtained by the reaction of the fuel with oxygen. The fuel contains as combustible components, mainly carbon and hydrogen, which react with the supplied oxygen (and possibly with any steam and carbon dioxide as may be present) to form carbon monoxide and hydrogen. At some temperatures it is also possible to form methane.
There are at least two different processes for the partial combustion of solid fuel. In the first process, solid fuel in particulate form is contacted with an oxygen-containing gas in the reactor in a fixed or fluidized bed at a temperature below about 1000C. A drawback of this method is that not all types of solid fuel can be partially combusted in this manner. For example, high swelling coal is unsuitable since particles of such coal type easily sinter, resulting in risk of clogging of the reactor.
A more advantageous process passes the finely divided fuel in a carrier gas such as nitrogen or synthesis gas into a reactor at relatively high velocity. In the reactor a flame is maintained in which the fuel reacts with oxygen-containing gas at temperatures above 1000C. The carbonaceous fuel is usually passed into the reactor via a burner, and the oxygen-containing gas is also passed via the burner into the reactor. In some processes a moderator gas such as steam or carbon dioxide is admixed with the oxygen-containing gas passed via the burner to the reactor; such a moderator gas is often advantageous for reducing or preventing premature contact of the oxygen with the reactor gas, which might result in undesirable complete conversion of the reactor gas.
The present burner is well suited to introduce the reactants horizontally into the reaction zone of a conventional, refractory lined partial oxidation gas generator, also referred to herein as a reactor, or gasification apparatus. It is particularly suited for use in solid fuel gasification apparatus having a plurality of burners for the reactants positioned on the periphery of the combustion zone, whereby the burner jets impinge on or near each other to facilitate the partial oxidation process and to minimize erosion of the refractory wall.
Since flame temperatures may exceed 3000.degree. C. or more, a primary concern of such burners is to prevent damage to the burner front, also referred to as the burner face, caused by the high heat flux and the potentially corrosive environment during the gasification process. To protect the burner front from overheating, it is conventional to provide a refractory lining applied to the outer surface of the burner front wall and/or provide a hollow wall member with internal cooling passages through which cooling fluid is circulated at a rapid rate. The present invention provides an improved burner having an internal structure wherein the cooling fluid is caused to flow in a particular manner to assure against possible high corrosion rates and to obtain even cooling over the burner front so as to minimize thermal stresses all of which could cause deterioration and even failure of the burner during prolonged operation.
A further advantage of the present burner configuration is the smooth curvilinear burner face dimensioned so as to facilitate durability in the presence of the corrosive atmosphere and heat flux resulting from the gasification reaction. The curvilinear front enables the burner front face construction to be relatively flexible, whereby it can withstand relatively high local heat flux without developing local thermal stress which could lead to failure.